Circadian variations in the risk of urinary calcium oxalate stone formation

OBJECTIVE: To evaluate the circadian fluctuations in the risk of urinary calcium oxalate stone formation with regard to critical periods of crystallization. PATIENTS AND METHODS: Over a given time period, the Tiselius index depends on urine volume and urinary excretion of oxalate, calcium, citrate and magnesium. This crystallization potential was evaluated during three successive periods spread over 24 h for 25 recurrent stone-formers aged 16-76 years (mean 50) and 25 control subjects aged 27-71 years (mean 44). RESULTS: There was no significant difference in the value of the Tiselius index for all equivalent time periods in both groups of patients. The minimum value was recorded in the afternoon and the circadian pattern of the index illustrated the predominant importance of urinary output in its determination. Morning urinary concentrations and excretions of citrate, and nocturnal levels of magnesium were significantly higher in the stone-formers when compared with the control subjects. CONCLUSION: The lithogenic risk for calcium oxalate stones was maximal at the end of the night or during the early morning, when urinary output was minimal. This circadian study revealed abnormalities that are not apparent from non-fractionated 24 h urine samples, and which were potentially relevant to therapy.     

Uropontin in urinary calcium stone formation

Normal urine is frequently supersaturated with respect to calcium oxalate. Thus, urinary inhibitors of crystallization appear to have an important role in preventing urinary stone formation. Uropontin was isolated by monoclonal antibody immunoaffinity chromatography and has the same N-terminal sequence as osteopontin derived from bone. This urinary form of osteopontin is a potent inhibitor of calcium oxalate monohydrate crystal growth at concentrations (approximately 0.1 microM) that normally prevail in human urine. Interaction with calcium oxalate monohydrate in vivo was shown by analysis of EDTA extracts of calcium stones. Uropontin is an abundant component of calcium oxalate monohydrate stones and present in only trace quantities in calcium oxalate dihydrate and hydroxyapatite stones. However, the precise role of uropontin in the pathogenesis of urinary stone formation is not known and is the subject of ongoing investigations.     

In vitro crystallisation systems for the study of urinary stone formation

Hydroxyapatite orbital implants undergo early ingrowth of fibrovascular tissue after enucleation. This animal study determined whether control and osteogenin-impregnated hydroxyapatite orbital implants vary in their osteogenic response at 6 and 52 weeks. Rabbits underwent enucleation with implantation of control or osteogenin-impregnated hydroxyapatite spheres. Light microscopy determined fibrovascular ingrowth, and histomorphometry quantitated the amount of bone produced. Osteogenin implants vascularized at a faster rate and contained bony foci by 6 weeks that became confluent at 1 year. Spontaneous osteogenesis was not seen in control animals at 6 weeks. After 1 year they contained bone, although less than in the osteogenin implants. Mixed cell inflammation was observed at the hydroxyapatite-tissue interface in both groups. No inflammation was noted at the interface of hydroxyapatite and bone. These are the first controlled observations that bone-specific differentiation occurs in the pores of spherical hydroxyapatite implants within the soft tissues of the socket. This vascularized process can be enhanced with osteogenin to occur earlier and more uniformly in the implants at one year.     

Dietary calcium, dietary protein, and kidney stone formation

Kidney stone disease is common and is a major cause of morbidity involving the urinary tract. Rising incidence rates of calcium oxalate stone disease, the most common type of kidney stone, have focused attention on dietary habits and their potential role in the development of nephrolithiasis. Traditionally, calcium restriction had been recommended to reduce the likelihood of calcium stone formation, but recent evidence suggests that dietary calcium restriction may actually increase the risk. Observational and experimental data suggest that restriction of animal protein may lower the risk of stone formation, but a randomized trial did not confirm this finding. Dietary modification may play an important role in reducing the likelihood of stone recurrence. Notably, dietary calcium restriction should be avoided in patients who have had a calcium oxalate kidney stone.     

The effect of ascorbic acid ingestion on the biochemical and physicochemical risk factors associated with calcium oxalate kidney stone formation

Current information on the pathophysiology, diagnostic process, and treatment of growth hormone deficiency is provided. A case study is provided that shows the positive effects of growth hormone therapy on a patient and his family. Information regarding the intravenous clinician's role in administration of growth hormone and patient teaching also is included.     

Differential expression of urinary inter-alpha-trypsin inhibitor trimers and dimers in normal compared to active calcium oxalate stone forming men

PURPOSE: We determine if the immunoreactive profile of urinary inter-alpha-trypsin inhibitor can be used to distinguish between normal individuals and individuals with calcium oxalate stone disease. MATERIALS AND METHODS: Urinary proteins were dialyzed against water (15 kDa. molecular weight cutoff), lyophilized and resolved by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (6% acrylamide, reducing conditions) followed by Western blot. Inter-alpha-trypsin immunoreactive proteins were detected by enhanced chemiluminescence. Stone formation was confirmed to be active radiologically or passed as stone or gravel within 12 months of the sample. Stone composition was confirmed crystallographically. Normal individuals had no personal or familial history of urolithiasis and matched stone forming patients regarding race (white) and age (23 to 71 years old). Urine from a total of 101 individuals was analyzed. RESULTS: The intact inter-alpha-trypsin trimer (approximately 220 to 240 kDa.) and heavy chain (HC) 2-bikunin/HC1-bikunin dimers (approximately 115 to 130 kDa.) were detected more often in stone forming men (23 of 26 [89%] and 26 of 26 [100%], respectively) than in normal individuals (6 of 26 [23%] and 5 of 26 [19%], respectively, p < 0.0001). In those normal individuals who expressed inter-alpha-trypsin trimer and HC-bikunins the relative intensities were 5.3+/-1.4% and 16.3+/-17.1% of the stone forming controls, respectively. The identity of high molecular weight-inter-alpha-trypsin immunoreactive bands was confirmed using antibodies against the individual subunits (HC1, HC2, HC3, bikunin). In contrast to men high molecular weight-inter-alpha-trypsin's were readily detected in normal and stone forming women with equal frequency (inter-alpha-trypsin-trimer p=0.1337, HC-bikunins p=0.2836): inter-alpha-trypsin-trimer 17 of 18 [94%] and 9 of 13 [77%]; HC-bikunins 17 of 18 [94%] and 10 of 13 [85%]). Inter-alpha-trypsin-trimer and HC-bikunins, respectively, were detected in 2 and 5 of 10 patients with chronic renal disease. Expression was not related to hematuria or proteinuria. CONCLUSIONS: Immunoreactive profiles of urinary proteins may be able to be developed into a useful diagnostic tool to identify active stone formation, although a separate panel may be required for men and women. It is possible that these differences may provide clues as to why the incidence of stone disease is higher in men than women.     

Renal metabolic changes relating to calculogenesis in an experimental model of calcium containing renal stone formation in rabbits

In histochemical studies it was shown that sulfated acid glycosaminoglycans (AGAGS) were produced and secreted into the tubular lumen in renal papilla, but not in the renal cortex of muddy stone forming kidney. There was no secretion of sulfated AGAGS in renal papilla histochemically during hydronephrosis before stone formation. On autoradiographic study with the use of 45Ca and 35S for labeling of sulfated AGAGS, we found that 45Ca accumulated in renal papilla of muddy stone forming kidney, but not in the other. 35S apparently accumulated into muddy stones. Measurement of calcium content of the renal papilla and cortex proved the results of autoradiographic studies, and measurement of uronic acid in the urine showed increased secretion of AGAGS in the urine from muddy stone forming kidney. From these results it was proposed that the sulfate AGAGS secreted in the urine could bind calcium crystals to each other amd make crystals aggregate massively.     

Crystallization and stone formation inside the nephron

A model is presented visualizing the events leading to calcium-salt, crystal- and stone-formation inside the nephron. For each nephron segment, handling of urine components relevant to stone formation is considered and urine composition determined. This information was applied to nucleation experiments simulating passage of urine through a nephron. The model and in vitro experiments suggest that within normal transit times for the respective nephron segments, particles of a hydroxyapatite-like material first form near the bend in the Loop of Henle of juxtamedullary nephrons. From there on, calcium oxalate particles start to appear: first dihydrate, then monohydrate. In the collecting duct system, particle size increases primarily due to crystal agglomeration. Several conclusions with clinical and experimental relevance can be drawn. An increase in urinary volume does not decrease the chance of crystal formation in the Loop of Henle, but does decrease passage time through the collecting ducts, and thus, the time allowed for large particle formation. A calcium load does not increase the risk for nucleation up to the distal tubule, but does increase the risk of large particle formation in the collecting ducts. An oxalate load increases the chance for nucleation throughout the nephron. For experiments simulating crystallization processes occurring inside the nephron, diluted urines should be used. They should be diluted 16 to 50 times for testing nucleation, 2 to 30 times for testing crystal growth, and 2 to 20 times for testing crystal agglomeration. Undiluted urines may be used to mimic conditions in the pelvis and the bladder.     

Seasonal variations of urinary stone colic in Arabia

The western region of Saudi Arabia is an area with a high prevalence of urolithiasis. This study was designed to find the effect of climatic changes on the occurrence of urinary stone colic as well as the effect of Ramadan fasting and pilgrimage festival. The emergency room (E.R.) records at King Abdulaziz University Hospital in Jeddah were studied for 3 consecutive years. Males diagnosed as urinary colic during this period were recorded on monthly basis with correction for 30 days a month. Data were recorded before, during and after the fasting month as well as before and after the pilgrimage festival. The results showed a steady increase in urinary stone colic in the hot season with a maximum rate in the months of June, July and August. The mean number of males with stone colic in these months was 45.33, 44.19 and 45.16 respectively. The lowest number was in March (28.06) with a rate of 4.11 per 1000 patients. A strong correlation was found between urinary stone colic and both temperature and atmospheric pressure with a P value of < 0.0001. No significant correlation was observed with relative humidity and similarly no significant change in relation to Ramadan fasting or the pilgrimage festival. These results suggest that there is a clear stone season in this area corresponding to the hot summer months. No significant increase in urinary stone colic was observed in relationship to the fasting month of Ramadan or the pilgrimage festival.     

Reduction of urinary stone recurrence by dietary counseling after SWL

To reduce the recurrence rate of or urolithiasis, dietary counseling was conducted for calcium-stone patients. Sixty-six patients received dietary counseling and were in principle instructed to use the Recommended Dietary Allowance for Japanese as their goal. Seventy-three patients did not undergo the counseling. Comparison of the dietary intake of the patients with the dietary requirements for Japanese revealed that protein intake, especially animal protein intake, was higher and calcium intake lower in the patients. As a result of the counseling, intakes of total protein, animal protein, fat, and carbohydrates were all reduced. Patients in the stone recurrence-free group excreted less oxalate than those in the recurrent one. The excretion of oxalate was then reduced and urine volume increased owing to the diet counseling program. The stone recurrence rate of the group participating in the diet counseling was lower than that of the group not taking part. The recurrence rate of the hyperoxaluric group was higher, with statistical significance, than that of the normooxaluric group among those not receiving the dietary counseling. With dietary counseling, the recurrence rate significantly decreased in the hyperoxaluric patients. Thus, the reduction in the rate of stone recurrence resulting from participation in the diet counseling program seemed to be attributable to the decrease in urinary oxalate excretion. Dietary counseling seems to be a useful measure to prevent urinary stone recurrence.     

Role of agglomeration in the early stages of papillar stone formation

Possible effects of crystal agglomeration on the early stages of calcium oxalate papillar stone formation are evaluated. The collecting ducts are filled with liquid that flows laminarly as established through hydrodynamical and physicochemical considerations. Under such conditions, agglomeration due to laminar shear forces proceeds. Agglomeration of calcium oxalate monohydrate crystals present in urine at a concentration typical for clinically observed crystalluria cannot result in the formation of a particle sufficiently large enough to be retained in the Bellini's duct and become a papillar stone nidus (nucleus). Formation of such an aggregate during the passage time of urine through the duct requires an unrealistically high concentration of crystals in urine, one that exceeds the normal content of urinary oxalate by several orders of magnitude. Aggregates obstructing the Bellini's duct as assumed in the free particle theory cannot represent a major factor in stone formation. This conclusion is corroborated by experimental results and other observations.     

Simple determination of urinary aldosterone without chromatography]

Previously acquired continuous avoidance performance of pigs in a shuttle-box was modified by a Pavlovian fear-conditioning procedure. Diazepam (1 mg/kg) given before the Pavlovian conditioning session prevented the increase in corticosteroids and the impairment of performance in the subsequent test session before the presentation of the fear signal. Diazepam given before the Pavlovian conditioning session and/or the test session did not prevent the increase of response to the CS presentation; however, the temporal pattern of increase differed according to the drug condition: the diazepam treatment on the day of the test significantly delayed the peak of responding to the CS; in pigs treated with diazepam on the day of Pavlovian conditioning and with saline on the day of test, the increase of response was diffuse instead of being localized to the CS presentation period. Pigs treated with diazepam both during learning and performance of fear conditioning showed some evidence of performance facilitation. Usual unitary interpretations cannot account for such results which would appear to be the net result of several intermingled effects among which state-dependent learning, acquisition deficit, and performance facilitation seem to be of importance.     

Comparison of relative risks of urinary stone formation after surgery for ulcerative colitis: conventional ileostomy vs. J-pouch. A comparative study

The main techniques which have been used to study skin microcirculation in patients with peripheral arterial occlusive disease include intravital microscopy with and without the use of fluorescent dyes, laser Doppler fluxmetry and transcutaneous oximetry. In patients with severe ischaemia (rest pain or incipient gangrene) the number of perfused skin capillaries is reduced. Parallel to the decreased number of microvessels containing blood, transcutaneous oxygen tension is low or even approaches the zero level. The tendency to oedema formation is documented by increased leakage of intravenously injected sodium fluorescein at the capillary apex of foot skin ('candlelight phenomenon'). Laser Doppler flux at rest may still be within the normal range even in advanced disease, since the sample volume of these instruments also contains non-nutritive shunt vessels. However, reactive hyperaemia after arterial occlusion is decreased and delayed in peripheral ischaemia. Whereas rhythmic low-frequency vasomotion is significantly enhanced in patients with intermittent claudication, vasoparalysis with no flux fluctuations prevails in patients with critical ischaemia.     

韶钢烧结矿喷洒CaCl2溶液工业试验

叙述了韶钢烧结喷洒ＣａＣｌ２溶液工业试验的经过和结果。工业试验表明,烧结矿喷洒ＣａＣｌ２溶液后对降低高炉上部炉料的低温还原粉化,改善料透气性,促进炉况 起到了较大作用。喷吹ＣａＣｌ２溶液的浓度为３％,喷吹量为１％时效果较 炉可增产３．２％,降低焦比１．５％。     

Sialic acid determinations of serum and urine specimens in calcium-containing urinary stone formers

PURPOSE: The aim of the present study was to compare sialic acid concentrations of serum and urine specimens in both calcium (Ca)-containing urinary stone formers and non-stone formers. Moreover, we studied inhibitory activity of sialic acid upon the calcium oxalate (CaOx) crystal aggregation and growth. MATERIALS AND METHODS: Sialic acid determinations were done on fresh serum and urine samples of 35 Ca-containing urinary stone formers (stone formers group) and 20 non-stone formers (patient controls group). Inhibitory activity of sialic acid upon the CaOx crystal aggregation and growth was studied by using in vitro assay method of seed crystal system. RESULTS: Serum sialic acid concentrations were found to be similar in the two groups. Urinary sialic acid concentrations were significantly lower in the urine specimens of stone formers than in their patient controls. Sialic acid showed a dose dependent inhibitory activity upon the CaOx crystal aggregation and growth into seed crystal method. CONCLUSION: It is suggested that urinary sialic acid may play some role during the phase of stone formation from the results of the present study, because sialic acid shows marked inhibitory activity upon the CaOx crystal aggregation and growth at concentrations higher than 100 mg/dl.     

Heparin sulfate in the stone matrix and its inhibitory effect on calcium oxalate crystallization

The nature of the soluble stone matrix and its possible role in urinary stone formation was studied. For this purpose we performed two-dimensional cellulose acetate membrane electrophoresis of the glycosaminoglycans (GAGs) which were contained in the soluble stone matrix, substances adsorbed onto calcium oxalate crystals in vitro (crystal surface binding substances, CSBS) and urinary macromolecules (UMMs). The main GAG in the soluble stone matrix and CSBS was found to be heparan sulfate, whereas the UMMs contained various GAGs usually seen in urine. An inhibition assay showed the soluble stone matrix to have the strongest inhibitory activity among these macromolecular substances when inhibitory activity was expressed in terms of uronic acid concentration. It is suggested that the main GAG in the soluble stone matrix consists of heparan sulfate, which has a strong inhibitory activity on calcium oxalate crystal growth and aggregation and constitutes part of the CSBS.